The field of the present invention is that of electrical connector termination arrangements utilized with flexible conductors. More particularly, the field of the present invention is that of clock spring interconnectors and electrical connector terminations utilized therein.
An increasing number of automotive vehicles have inflatable supplemental occupant restraint systems (commonly referred to as air bag assemblies.) An air bag assembly for the driver is typically located on the steering wheel facing the driver. The air bag assembly must be in continuous electrical connection with acceleration sensors in the car body (this connection is typically through a restraint control module). In a frontal crash the sensors provide a control electrical signal to an air bag inflator which instantly inflates an air bag envelope in the event of a predetermined vehicular deacceleration.
There is a need for an electrical interconnection between a rotatable portion of the air bag assembly which is mounted on the steering wheel, and a remaining portion of the air bag assembly and/or wiring which is mounted in a stationary position inside the steering column. Electrical interconnectors between rotatable and stationary parts are well known. Typically, a rotatable electrical interconnector includes an electrical brush which rests upon a conductive ring. However, there is a perceived slight risk, particularly during the impact of an accident, of a transient interruption of electrical connection with a brush and ring system, which could possibly result in a malfunction of the air bag assembly. Accordingly, Federal Motor Vehicle Safety Standards (FMVSS) have been promulgated requiring continuous-type electrical interconnectors.
One example of a continuous-type electrical interconnector is a clock spring interconnector which includes an outer housing and a rotor hub. The housing and rotor hub rotatably are associated with one another at a plurality of bearing surfaces. An elongated xe2x80x9cclock springxe2x80x9d is located inside the interconnector. The clock spring is formed from a plurality of electrical leads referred to as conductors which are encased by polymeric tape such as Mylar(copyright). The clock spring is conductively attached at both ends to conductor terminal pins that pass out of the interconnector to unite the air bag assembly to the aforementioned sensors. The clock spring interconnector is mounted on the steering column, allowing a steering wheel to be rotated in either direction while a continuous, positive electrical connection is provided between air bag assembly and sensors via the clock spring interconnector.
Recently, more advanced passenger restraint systems have been brought forth. An advanced passenger restraint system includs several sensors that are used to classify and/or locate the front seat occupants. The classification and location data is in turn used to optimize the restraint system to a particular combination of occupants and their positions in crash scenarios. For example, a smaller occupant seated close to the steering wheel may not warrant an air bag deployment in some crash events while a larger occupant seated well away from the steering wheel or far back in the passenger seat may receive a maximum power air bag deployment. Other combinations of occupant class and position may receive a partial air bag deployment. The advanced restraint system accordingly requires more electrical conductor lines between a restraint control module and the air bag assembly in the steering wheel. Additionally, in premium vehicles, it is often desirable to have other various vehicle control functions actuated by control buttons placed on the steering column such as the heating, ventilating and air conditioning system of the vehicle and also the turn signals, cruise control and the sound system for the vehicle. It may be desirable to have these other various controls be electrically interconnected through the clock spring.
Regardless of the above-noted desires, there is a physical limitation upon the width of the clock spring. The amount of space that the clock spring occupies is limited due to space considerations in the interior of the vehicle. To allow for the different electrical functions to be facilitated by the clock spring, the spacing or pitch between the conductor lead lines is minimized. The conductor leads of the clock spring are contained between two layers of dielectric material. To attach the conductors of the dielectric material to terminal pins which are fixed with respect to the steering wheel or steering column, a stamped terminal design is utilized. The terminal pins are stamped in a generally L-shaped manner to achieve terminals with the least amount of mass as possible. The terminal pins are stamped from a flat sheet metal of conductive foil. The terminal pins, in a simultaneous operation, are connected to their various conductor leads of the conductive tape and thereafter are slit to separate them to achieve independent electrically conductive paths.
The conductors of the clock spring tape may be thin wires or may be a powdered metal which is positioned by the dielectric tape material. Accordingly, the pitch achievable on the clock spring tape is very small and is not a limiting function in clock spring interconnector design. In contrast, the terminal pins as previously mentioned, are stamped from a common sheet of foil conductive material. Due to the limitations of present commercially viable stamping technology, the pitch or spacing between the pin terminals from center to center at a minimum should be approximately 1.5 times the thickness of the foil material plus xc2xd the width of the pin. Therefore, if the pitch of the leads of the clock spring is too small there is no present way of economically providing for their electrical connection to a stamped pin terminal. Accordingly, for a clock spring interconnector with an ever increasing amount of electrical leads, a width (height) of the clock spring interconnector becomes excessive and makes it non-feasible for use between the steering wheel and steering column.
It is desirable to provide an electrical termination arrangement between a multiple lead conductive flexible tape which is operatively associated with a first member and a stamped terminal having pins corresponding to the multiple leads of the tape wherein the pins are connected with a second member which is non-positionally affixed with respect to the first member and wherein the height of the flexible tape can be minimized.
To make manifest the above delineated and other desires a revelation of the present invention is brought forth. A preferred embodiment of the present invention provides a termination arrangement which is particularly useful in clock spring electrical interconnectors. The termination arrangement of the present invention includes a multiple lead conductive flexible tape having first and second ends. The first end of the tape is operatively associated with a first member. A stamped terminal is provided. The terminal has pins corresponding to the multiple leads of the tape. The terminal pins have a first end for connection with a second member which is non-positionally affixed with respect to the first member. The pins of the terminal are parallel spaced from one another with a pin-to-pin center distance of approximately 1.5 times a thickness of a sheet of material the terminal pins are stamped from plus xc2xd the width of the terminal pins. The terminal pins serially increase in length. The terminal pins contact the leads of the tape in a serially lateral increasing manner. Accordingly, the spacing between the leads of the tape is generally substantially less than the spacing between the terminal pins. Accordingly, the width of the flexible tape can be minimized without regard to whether or not a stamped pin terminal can be provided which matches the pitch of a flexible tape which has its width held to a minimum value.
It is an advantage of the present invention to provide an electrical termination arrangement of a flexible tape conductor to a stamp pin terminal. It is another advantage of the present invention to provide an electrical termination arrangement as described in a clock spring electrical interconnector. Other advantages of the invention will become more apparent to those skilled in the art from a reading of the following detailed description and upon reference to the drawings.